In order to provide a convoy configured from multiple vehicles to travel, various kinds of convoy travel control devices are known (e.g., Japanese Patent. No. 3358403 corresponding to U.S. Pat. No. 5,680,122A). A convoy travel control device is mounted on each vehicle of the convoy, and performs a travel control of each vehicle. Behavior of each vehicle configuring the convoy travel during the convoy travel may be described as if one vehicle was connected to another vehicle in front of the one vehicle or behind the one vehicle. Thus, the convoy travel is referred to as a connected travel.
In the convoy travel control device disclosed in Japanese Patent No. 3358403, when a subject vehicle is in an automatic travel mode, the subject vehicle performs the convoy travel with a preceding vehicle if possible. Only when a driver performs a separation instruction about the convoy travel, the subject vehicle separates from the convoy.